1. Field of the Invention
The present invention relates to a homopolar dynamoelectric machine.
2. Description of the Related Art
In a known homopolar dynamoelectric machine, the dynamoelectric machine is provided with a solenoid coil for excitation, having a cylindrical cavity formed around an axis thereof; and a rotor, located within the cavity, rotatable about the axis of the coil. The dynamoelectric machine is further provided with a first electric current path extending from a proximal portion to a distal portion of the rotor; and a second electric current path extending from a distal portion to a proximal portion of the rotor. The second path is connected to the first path in series (see Japanese Unexamined Patent Publication No. 49-129103). In this dynamoelectric machine, on a surface which defines the cavity, that is, for example, an inner surface of the coil holder for holding the solenoid coil, there is fixed a stationary member extending radially inwardly from the inner surface. The first path may be formed in the rotor, and the second may be formed in the stationary member.
On the distal end of the stationary member, a nozzle for injecting an electroconductive liquid toward the distal end of the first path is provided, and an electrical connection between the distal ends of the first and second paths is thereby obtained. However, when the distance between the rotor and the stationary member becomes smaller than suitable, an undesirable contact between the rotor and the stationary member may occur. On the other hand, when the distance is larger than suitable, it is difficult to ensure an electrical connection between the first end second paths at their distal ends. Therefore, in the dynamoelectric machine described above, an accurate location of the rotor and the stationary member is required. The rotor and the stationary member, however, are located in the cavity of the solenoid coil, which cavity is relatively small, and thus it is difficult to locate these elements in the inner space accurately so as to make the distance between the rotor and the stationary member suitable. As a result, an assembly of the homopolar dynamoelectric machine is difficult, and it is difficult to ensure an electrical good connection between the first and second paths.